The present invention relates to seed planters for dispensing individual seeds at a controlled rate into a seed furrow, and specifically, to an adjusting mechanism controlling the down pressure on a planter unit.
Seed planters dispense seeds at a controlled rate into a seed furrow as a planter is advanced along the ground. In a typical arrangement, a tractor is coupled to tow a toolbar to which is attached, in parallel spaced apart relationship, a plurality of planting units.
Each planting unit typically includes a seed hopper and a seed meter for dispensing seeds at a controlled rate as the planting unit moves over the ground. The planting unit may include on its lower surface a furrow-opening disk for opening a furrow for the seeds, a furrow closing disk for closing the furrow about the seeds, and a trailing wheel that tamps the earth down on the furrow. In order that these disks and wheels properly engage the soil, the planting unit may be coupled to the tow bar with a pivoting four-bar linkage. A tension spring mounted between the tow bar and one of the arms of the linkage provides a downward pressure on the planting unit ensuring that it tracks the ground surface regardless of changes in height of the tow bar relative to the surface under the planter.
It may be desirable to adjust the down pressure on the planting units according to the condition of the field. A soft till field may require less pressure, for example, than a field with no till and greater surface irregularity. For this purpose, the tension spring may have a threaded adjuster or the like that may be turned to change the tension on the spring.
Changing the down pressure on many planting units using a threaded adjuster can be time consuming. The threaded elements are prone to contamination or corrosion making it difficult to turn the adjusters without special tools and the nature of the adjustment process makes it difficult to provide consistent down pressure on multiple planting units.